Quantification of precipitate fraction in Al-Si-Cu alloys

Quantification of precipitate fraction is difficult when the precipitates formed are of low volume fraction. A simple method is proposed in the present work to estimate the precipitate fraction of Al2Cu phase in Al-Si-Cu alloys based on X-ray diffraction analysis. The change in the lattice parameter of the matrix due to ageing, measured from X-ray diffraction profiles, is correlated to the fraction of Al2Cu phase formed during ageing. JMatPro, a software package for calculating the properties of metallic systems, is used to calculate the phase constitution and composition in the Al-Si-Cu alloys studied after different heat treatments. Factors that affect the lattice parameter of the matrix have been discussed and considered in the calculations.